(I) Field of the Invention
This invention relates to a method of producing a laminate to the surface of which a chemical plating is to be applied, particularly, to a method of producing a laminate exhibiting a high heat resistance and permitting a chemical plating layer to be formed on the surface satisfactorily. This invention relates also to a method of producing a laminate with a metalized surface.
(II) Description of the Prior Art
In applying a chemical plating to the surface of a laminate such as a paper-phenolic resin laminate, a glass-epoxy resin laminate or a paper-epoxy resin laminate, it was customary to coarsen the laminate surface in advance by means of, for example, a honing treatment. Certainly, the coarsening treatment permits facilitating the metal deposition to the laminate surface and improving to some extent the bonding strength of the formed plating layer to the laminate. But, the laminate itself used in this field fails to exhibit a heat resistance high enough to withstand a soldering operation applied to the metalized surface of the laminate.
It was also customary to form an adhesive layer on the laminate surface. For example, a peelable sheet is coated with an adhesive containing a butadiene-based rubber as the main component. The adhesive coating, while in a semi-cured state, is brought into contact with a base material such as a pre-preg, followed by heating the coating under pressure so as to cure the coating. Then, the sheet is peeled off the cured adhesive coating and a chemical plating is applied to the exposed surface of the coating. Certainly, the plating metal is effectively deposited on and strongly bonded to the adhesive layer. But, the resin molecules contained in the base material, e.g. pre-preg, are diffused into the adhesive layer in the heating step under pressure so as to impair the intrinsic properties of the adhesive layer.